A vacuum circuit breaker is the kind of circuit breaker where the arc quenching takes place in vacuum. The technology is mainly suitable for medium-voltage applications. Vacuum technology for higher voltage has been developed, but is not yet commercially viable.
The operation of opening and closing current that carries contacts and associated arc interruption is taking place in a vacuum chamber in the breaker and is called a vacuum interrupter.
The vacuum interrupter consists of a steel arc chamber in the centre, symmetrically arranged inside ceramic insulators. The vacuum pressure inside a vacuum interrupter is normally maintained at 10 – 6 bar.